Process of leaching ores or tailings.



" NITED STATES PATENT FFICE.

EDWARD H. DIOKIE, OF BODIE, CALIFORNIA, ASSIGNOR OF ONE-THIRD TO JAMESKANE, OF SAME PLACE.

PROCESS OF LEACHING ORES OR TAILINGS.

SPECIFICATION forming part of Letters Patent No. 656,395, dated August21, 1900.

Application filed April 2, 1900. Serial No. 11,244, (No specimens.)

To ctZZ whom it may concern;

Be it known that I, EDWARD H. DICKIE, a citizen of the United States,residing at Bodie, county of Mono, State of California, have invented anImprovement in Processes of Leaching Ores or Tailings; and I herebydeclare the following to be a full, clear, and exact-description of thesame.

My invention relates to improvements in the leaching of ores, tailings,and like material containing valuable precious metals in conjunctionwith a cyanid solution, and is especially designed for use in connectionwith such ores or tailings as contain base substances which will actupon the cyanid in the solution and render it unfit to dissol thprecious metals.

It consists in the employment of an agent having little or no affinityfor the precious metals, but which will readily unite with that portionof the base substance which would otherwise be attacked by the cyanidand render the latter useless as a dissolving agent for gold and silver.

In leaching ores or tailings which contain lead, zinc, copper, andcertain pyrites of these or of iron by what is known as theMacArthur-Forrest process of cyanid leaching or other kindred processesthe base metals or substances are acted upon by the cyanid in thesolution, and entering into the solution they render it unfit todissolve the precious metals. The solution is then in the conditionknown as fouled solution. As the base substances uniting with the cyaniddestroy its power of dissolving the gold and silver for which it isnormally intended, it thus becomes neutralized and of no efiect byreason of this combination. I have discovered that acetic acidneutralized with lime in the cyanid solution or potassium acetate useddirectly in the solution while having little or no affinity for theprecious metals will readily unite with that portion of the base metalsor substances which would otherwise be attracted by the cyanid. I havefound by us-. ing the potassium acetate direct in the cyanid solution Iobtain equally-good results as when acetic acid and lime or otherequivalent agent is used to neutralize'the acid, the potassium acting asa carrier for the acid and neutralizing it so far as any effect that itwould have upon the cyanid is concerned, but leaving it free to unitewith the base substances-such as lead, zinc, copper, &c.--previouslymentioned and forming acetates of these. This addition also assists inprecipitating the gold and silver on the zinc shavings or sponge whichis employed in the cyanid process for that purpose, because the aceticacid or acetate combined with the cyanid solution acts to prevent thedeposit of the base metals on the zinc shavings, and, furthermore, thatthe action of the acetate upon the zinc keeps it clean and in goodcondition to receive the deposit of gold and silver. It also acts toprevent the fouling of the cyanid solution by the presence of foreignmatter in an organic statesuch as dead leaves, decomposed wood, and vegetable matter-which is often unavoidablyintroduced into the vats.

While the proportions used in my solution must necessarily varywith thecharacter of the ore to be treated, I have found the following to be avery practical solution for general mill use: potassium acetate, aboutonefifth, by weight, of the amount of cyanid potassium used withoutregard to the strength of the solution, this, being determined after theproper strength of solution is found for the particular material whichis to be leached.

Having thus described my invention, what I claim as new, and desire tosecure by Letters Patent, is-

1. The improvement in the process of leaching ores or tailings with asolution which dissolves the precious metals, which consists in addingto the solution an agent composed of an acetate of an alkali metal or ofalkali-earth metal which is capable of readily uniting with and formingacetates of the base metals,and which has little or no affinity for theprecious metals thereby enabling the solvent to act directly upon thelatter, and then leaching the ores.

2. The improvement in the process of leaching ores or tailings withcyanid solutions, which consists in adding to such solutions an parts ofpotassium cyanid to one part of ace- 1o tate, and then leaching theores.

In witness whereof I have hereunto set my hand.

EDWARD H. DICKIE.

Vitnesses:

JAMES KANE, A. N. J oNEs.

